Wondering if anyone else has experienced this.
Welcome to the board. Gastrointestinal problems can often be puzzling.
It sounds like your doctor has done a pretty thorough work-up and did not really find anything. Does the pain seem to be related in any way to eating? The timing or what you eat? I can't recall anyone else here reporting a problem like yours, but maybe someone will see your post and chime in.
Have you tried the chamomille tea again? It would be interesting to see if it brings relief again.